[T-lymphocyte activation. Studies on the function of mediator proteins (author's transl)].

The functions of several mediator proteins involved in the T-cell blastogenesis have been investigated 1. Newly described is the Plasmatic Human IL-2 Inducing Protein (PHILIP), a glycoprotein from human serum with a molecular weight of about 85,000 D. Its presence is mandatory for the synthesis and/or secretion of Interleukin-2 (T-cell growth factor). The mediator protein can be distinguished from other known serum glycoproteins (e.g., transferrin and plasminogen) by affinity chromatography. Desialylation completely abolishes its biologic activity. 2. PMSF- and DFP-treatment of conditioned culture medium inhibit the blastogenesis in the peripheral mononuclear blood-cell fraction. However, the growth of a permanent T-cell line in the inhibitor-treated medium is not affected. This indicates the existence of a blastogenic factor with serine-protease activity.